The invention is based on a pressure regulating valve and a method for producing a pressure regulating valve.
German Published, Unexamined Patent Application DE 197 54 243 A1 shows a pressure regulating valve of a fuel supply system. A supply line leads to the pressure regulating valve, and a line extending onward carries the fuel away from the pressure regulating valve. Depending on the change in magnitude of the fluid flow flowing through the pressure regulating valve, the flow resistances in the supply line and in the line leading onward vary. These fluctuations in flow resistances cause troublesome fluctuations in the pressure level that is to be regulated by the pressure regulating valve in the fuel supply system. Because especially the line leading onward is often relatively long and should have the smallest possible cross section, the flow resistances in the line leading onward fluctuate considerably, as a function of the magnitude of the fluid flow. As a result, the pressure level regulated by the pressure regulating valve undesirably fluctuates very greatly as well.
Additionally, in the pressure regulating valve shown in DE 197 54 243 A1, a damping device is provided, which is intended to prevent excessive oscillation of the closing body of the pressure regulating valve. However, in the known pressure regulating valve, the damping device has the disadvantage that for lack of an adequate flow through the damper chamber, gas can accumulate, which can very severely impair the damping action of the damping device. Another disadvantage is that the closing body has a complicated shape, making its production relatively complicated and expensive. Another disadvantage is that the tappet connecting the damper piston to the ball is immediately adjacent the closing body in the region of the valve seat, and as a result dimensional imprecisions arise that can lead to leakage, which cannot be allowed. A further disadvantage is that if adequate damping action is to be achieved, the damper piston must be guided with very tight play. This means the pressure regulating valve is severely vulnerable to dirt.
The pressure regulating valve according to the invention and the method for producing a pressure regulating valve have the advantage over the prior art that a substantially simpler to produce and markedly better-functioning pressure regulating valve is available. In particular, excellent values regarding tightness, pressure regulation quality, and the desired small structural size are attainable.
In particular, the advantage is obtained that whenever the closing body has lifted at least partly away from the valve seat, a pressure backs up upstream of the outflow throttle restriction, and this backed-up pressure additionally acts on the closing body in the opening direction. This has the advantage that when the fluid flow flowing through the pressure regulating valve increases, the closing body, at a large fluid flow, lifts increasingly far from the valve seat, and that as a result, as the fluid flow becomes larger, the flow resistance through the pressure regulating valve decreases. Since often in the line upstream of the pressure regulating valve and especially in the line downstream of the pressure regulating valve the resistance rises as the fluid flow increases, the possibility exists, because of this decreasing characteristic curve of the pressure regulating valve, of compensating for these flow resistances in the lines, so that the pressure to be regulated by the pressure regulating valve can be kept constant, largely independently of the magnitude of the fluid flow.
If the outflow throttle restriction is disposed on one side relative to the fluid opening, this has the advantage that the closing body is pressed unilaterally against its guide. As a result, conditions that are defined precisely in terms of hydraulics and mechanics are advantageously obtained in the region between the closing body and the valve seat and also between the closing body and the closing body guide. This has the advantage that the closing body rests eccentrically on one side on the closing body guide, always in the same way, and that as a result, an easily controlled, unchanging, predictable, constant regulating behavior of the pressure regulating valve is assured. Another advantage is that between the closing body guide and the closing body, always-constant, easily controlled frictional forces are assured. These frictional forces offer the advantage of an additional easily controlled damping. The overall result obtained is a constant, easily controlled regulating behavior of the pressure regulating valve.
Because the outflow throttle is provided radially outside the closing body guide, a relatively large annular gap is obtained around the valve seat between the closing body and the dividing wall, so that the fluid flowing through between the closing body and the valve seat can flow through with uniform distribution over the circumference and can then flow tangentially around the closing body in the direction of the outflow throttle restriction and can then flow out in the direction of the fluid continuation.
If the closing body guide is formed by a sheath and the outflow throttle restriction is provided in the sheath, in which case the outflow throttle restriction can be formed in a very simple way by a simple hole in the sheath, the overall result is an especially low production cost.
If the closing body is formed by at least one ball, this has the advantage of ease of manufacture, and very good quality is also attainable at low effort and expense.
If the closing body is formed by at least two balls solidly joined together, this has the advantage that especially good throttling with a relatively large gap is attainable at low production cost and effort for the delivery throttle opening. The relatively large gap that is allowed offers the advantage of less vulnerability to dirt, and production variations, which can never be avoided entirely, are not as critical. Another advantage is that if balls are used, canting of the closing body in the closing body guide need not be feared.
With the damping devise, through which the fluid flow flows constantly when the closing body is lifted from the valve seat, having the damper chamber, and with the delivery throttle opening and the discharge throttle opening, the advantage is attained that no gas bubbles can accumulate in the damper chamber. Because the damper chamber has a fluid flow flowing through it, even the smallest air bubbles or outgassing of fuel are entrained constantly by the fluid flow. This has the advantage that the damping action functions highly reliably.
Since a fluid flow constantly flows through the damper chamber when the fluid opening is at least partly open, and since where there is a throttle restriction the flow resistance typically rises quadratically as a function of the fluid flow, very good damping action is obtained. The damping action in this damping device is substantially greater than in a damping device that has a damper chamber without a flow through it. As a result, the flow cross-sectional areas of the delivery throttle opening and the discharge throttle opening can be substantially larger than in a damping device with a damper chamber that does not have a fluid flow flowing through it. Production is therefore substantially simpler, and in particular the dimensional and shape tolerances to be adhered to are not as close, and the damping device is substantially less vulnerable to dirt.
If the gap between the closing body and the closing body guide is used to act as a delivery throttle opening, this has the advantage that the delivery throttle opening can be produced without additional expense.
If the hole that forms the discharge throttle opening is disposed such that it points upward out of the damper chamber, this has the advantage that entrainment of gas bubbles from the damper chamber can be improved still further and is assured highly reliably.
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawing.